Biology subjects

Freeland, J.

Publications and source records attributed to Freeland, J..

7 recordsLinked to original sources

bioRxiv2025

Time in sympatry correlates with the strength of reproductive isolation in hybridising Typha

In North America, hybridisation between Typha angustifolia and T. latifolia results in the highly impactful T. x glauca. In Europe, where its parental taxa are also sympatric, T. x glauca is scarce, suggesting stronger reproductive isolation on this continent. Using genomic data from the two species in North America and Europe, we reconstructed their demographic histories and characterised barrier loci between them. Demographic modelling suggests that the initial contact between the two species in Europe occurred [~]800,000 years ago, indicating sympatry in that region since the Middle Pleistocene. In North America, their contact likely happened within the last centuries and was potentially driven by the human-mediated dispersal of T. angustifolia. We identified 47 candidate barrier loci between species in Europe, 6 of which are associated with reproductive functions. No barrier loci were found in North America. Our results suggest that prolonged sympatry can promote the evolution of reproductive barriers, whereas prolonged allopatry can reduce the likelihood of their development. Future studies could help determine whether time in sympatry is a predictor of the strength of reproductive isolation between hybridising taxa. Preventing invasions by hybrid taxa will require limiting the human-mediated dispersal of Typha (and other allopatric species) lacking reproductive isolation.

genomics↗

bioRxiv2024

PGC-1α drives small cell neuroendocrine cancer progression towards an ASCL1-expressing subtype with increased mitochondrial capacity

Adenocarcinomas from multiple tissues can evolve into lethal, treatment-resistant small cell neuroendocrine (SCN) cancers comprising multiple subtypes with poorly defined metabolic characteristics. The role of metabolism in directly driving subtype determination remains unclear. Through bioinformatics analyses of thousands of patient tumors, we identified enhanced PGC-1--a potent regulator of oxidative phosphorylation (OXPHOS)--in various SCN cancers (SCNCs), closely linked with neuroendocrine differentiation. In a patient-derived prostate tissue SCNC transformation system, the ASCL1-expressing neuroendocrine subtype showed elevated PGC-1 expression and increased OXPHOS activity. Inhibition of PGC-1 and OXPHOS reduced the proliferation of SCN lung and prostate cancer cell lines and blocked SCN prostate tumor formation. Conversely, enhancing PGC- 1 and OXPHOS, validated by small-animal Positron Emission Tomography mitochondrial imaging, tripled the SCN prostate tumor formation rate and promoted commitment to the ASCL1 lineage. These results establish PGC-1 as a driver of SCNC progression and subtype determination, highlighting novel metabolic vulnerabilities in SCNCs across different tissues. STATEMENT OF SIGNIFICANCEOur study provides functional evidence that metabolic reprogramming can directly impact cancer phenotypes and establishes PGC-1-induced mitochondrial metabolism as a driver of SCNC progression and lineage determination. These mechanistic insights reveal common metabolic vulnerabilities across SCNCs originating from multiple tissues, opening new avenues for pan-SCN cancer therapeutic strategies.

cancer biology↗

bioRxiv2023

A simple method to genetically differentiate invasive F1 Typha hybrids (T. x glauca) and advanced-generation/backcrossed hybrids from parent species (T. latifolia and T. angustifolia) in eastern Canada and northeastern USA

A widespread Typha (cattail) hybrid zone in southeastern Canada and northeastern USA comprises T. latifolia, T. angustifolia, and their hybrid T. x glauca. In this region the hybrid is considered invasive because of its detrimental impacts on wetlands and biodiversity. Researchers and managers are increasingly interested in tracking and controlling the spread of the invasive hybrid, but this can be hampered by challenges in differentiating taxa: while the parent species and F1 hybrids can often be identified from morphological characteristics, advanced-generation and backcrossed hybrids can be common, and these have obscured morphological distinctions among taxa. Here we present five species-specific genetic markers that differentiate T. latifolia, T. angustifolia, F1 hybrids, and advanced-generation/backcrossed hybrids. Unlike the pre-existing species-specific microsatellite markers, these markers require only PCR or PCR followed by a restriction enzyme digest, and can be visualized on an agarose gel. As a result, they require less specialized equipment than existing species-specific markers, and should therefore be useful for a larger group of practitioners. Future use of these markers could include monitoring range expansions, assessing the outcomes of restoration programs, and avoiding the unnecessary elimination of native Typha.

molecular biology↗

bioRxiv2022

Transformation of Human Mesenchymal Stem Cells into High-Grade Sarcomas by YAP1 and K-RAS Reflects the Undifferentiated Pleomorphic Sarcoma-Myxofibrosarcoma Disease Spectrum

High-grade complex karyotype sarcomas are a heterogeneous group of more than seventy tumors that vary in histology, clinical course, and patient demographics. Despite these clear differences, these high-grade sarcomas are treated similarly with a uniformly high metastatic rate. Pre-clinical models that allow for rigorous comparisons of distinct human sarcoma subtypes would advance insights into the relationships between sarcomas and inform therapeutic decisions. We describe the robust transformation of human mesenchymal stem cells into multiple subtypes of high-grade sarcoma. Using a pooled genetic screening approach, we identified key drivers and potential modifiers of transformation. YAP1 and KRAS were validated as drivers of two distinct sarcoma subtypes, undifferentiated pleomorphic sarcoma (UPS) and myxofibrosarcoma (MFS), respectively. In addition, the pathology of tumors driven by CDK4 and PIK3CA reflected leiomyosarcoma (LMS) and osteosarcoma (OS) indicating that further iterations of this model could result in additional sarcoma subtypes. Histologically and phenotypically these tumors reflect human sarcomas including the pathognomonic complex karyotype. In addition, CDK4 and PIK3CA driven tumors demonstrated endogenous YAP1 amplification which is seen across a subset of human tumors. While all tumors overlapped transcriptionally with the TCGA sarcoma data, further analysis confirmed that YAP1 and KRAS tumors recapitulate the UPS and MFS subtypes. Co-analysis of TCGA and model tumors support that these sarcoma subtypes lie along a spectrum of disease and adds guidance for further transcriptome-based refinement of sarcoma subtyping. Within complex karyotype sarcomas, there are multiple genetic changes but identifying those that are clinically relevant has been challenging. Comparing differentially expressed genes in YAP1 and KRAS tumors to human UPS and MFS identified the enrichment of oxidative phosphorylation pathways in both YAP1 tumors and UPS. Treatment of a panel of sarcoma cell lines with the combination of an oxidative phosphorylation inhibitor and Hippo pathway inhibitor led to a significant impairment in growth identifying new therapeutic targets. A subset of human UPS tumors showed an even greater enrichment in these pathways indicating this model can be used to identify clinically relevant subtypes. This model can be used to begin to understand pathways and mechanisms driving human sarcoma development, the relationship between sarcoma subtypes and to identify and test new therapeutic vulnerabilities for this aggressive and heterogeneous disease. Statement of SignificanceWe have created the first model to study the development, growth, and metastasis of multiple human sarcoma subtypes. This system can be used as a platform to investigate sarcoma biology and identify new therapeutic targets across a heterogeneous disease.

cancer biology↗

bioRxiv2021

Genome assembly, annotation and comparative analysis of the cattail Typha latifolia

Cattails (Typha species) comprise a genus of emergent wetland plants with a global distribution. Typha latifolia and T. angustifolia are two of the most widespread species, and in areas of sympatry can interbreed to produce the hybrid Typha x glauca. In some regions the relatively high fitness of T. x glauca allows it to outcompete and displace both parent species, while simultaneously reducing plant and invertebrate biodiversity, and modifying nutrient and water cycling. We generated a high-quality whole genome assembly of T. latifolia using PacBio long-read and high coverage Illumina sequences that will facilitate evolutionary and ecological studies in this hybrid zone. Genome size was 287 Mb and consisted of 1,189 scaffolds, with an N50 of 8.706 Mb; 43.84% of the genome were identified as repetitive elements. The assembly has a BUSCO score of 96.03%, and 27,432 genes and 2,700 RNA sequences were putatively identified. Comparative analysis detected over 9,000 shared orthologues with related taxa and phylogenomic analysis supporting Typha latifolia as a divergent lineage within Poales. This high-quality scaffold-level reference genome will provide a useful resource for future population genomic analyses and improve our understanding of Typha hybrid dynamics.

genomics↗

bioRxiv2020

Bent DNA bows as amplifiers and biosensors for detecting DNA-interacting salts and molecules

Due to the central role of DNA, its interactions with inorganic salts and small organic molecules are important for understanding various fundamental cellular processes in living systems, deciphering the mechanism of many diseases related to DNA damages, and discovering or designing inhibitors and drugs targeting DNA. However, there is still a need for improved sensitivity to detect these interactions, especially in situations where expensive sophisticated equipment is not available. Here we report our development and demonstration of bent DNA bows for amplifying, sensing, and detecting the interactions of 14 inorganic salts and small organic molecules with DNA. With the bent DNA bows, these interactions were easily visualized and quantified in gel electrophoresis, which were difficult to measure without bending. In addition, the strength of the interactions of DNA with the various salts/molecules were quantified using the modified Hill equation. This work highlights the amplification effects of the bending elastic energy stored in the DNA bows and the potential use of the DNA bows for quantitatively measuring DNA interactions with small molecules as simple economic methods; it may also pave the way for exploiting the bent DNA bows for other applications such as monitoring water quality and screening DNA-targeting molecules and drugs.

biophysics↗

bioRxiv2019

Faster diffusive dynamics of histone-like nucleoid structuring proteins in live bacteria caused by silver ions

The antimicrobial activity and mechanism of silver ions (Ag+) have gained broad attention in recent years. However, dynamic studies are rare in this field. Here, we report our measurement of the effects of Ag+ ions on the dynamics of histone-like nucleoid structuring (H-NS) proteins in live bacteria using single-particle tracking photoactivated localization microscopy (sptPALM). It was found that treating the bacteria with Ag+ ions led to faster diffusive dynamics of H-NS proteins. Several techniques were used to understand the mechanism of the observed faster dynamics. Electrophoretic mobility shift assay on purified H-NS proteins indicated that Ag+ ions weaken the binding between H-NS proteins and DNA. Isothermal titration calorimetry confirmed that DNA and Ag+ ions interact directly. Our recently developed sensing method based on bent DNA suggested that Ag+ ions caused dehybridization of double-stranded DNA (i.e., dissociation into single strands). These evidences led us to a plausible mechanism for the observed faster dynamics of H-NS proteins in live bacteria when subjected to Ag+ ions: Ag+-induced DNA dehybridization weakens the binding between H-NS proteins and DNA. This work highlighted the importance of dynamic study of single proteins in the live cells for understanding the functions of antimicrobial agents to the bacteria.

biophysics↗